German Bank Survey # 4 Results from 15/09/2024
Survey Details
6 commercial purse seiners conducted this fishing survey on 15/09/2024 starting at 20:00:00.
All vessels ran two transects in the German Bank box and two transect in the Seal Island Box.
There was a plankton tow and replicate conducted and CTD cast by Lady Melissa.
No tags were applied during this survey.
Samples were obtained for target strength estimation.
Acoustic Equipment
Each vessel was equipped with a Simrad ES38-18/200-18C combi (2-in-1) transducer prior to the survey that contains a 38kHz split beam and 200 kHz single beam transducer. Data was logged to the computer hard-drive for post-processing. All participating boats were calibrated on 38kHz before the survey.
Survey Results
Main Results
The results are subject to change as DFO will re-evaluate data editing, area estimation and apply a target strength.
Preliminary biomass prediction for German Bank using standardized parallel transects is 24,824mt, and with turnover applied 21,033mt. The preliminary biomass estimate for Seal Island is 1,369mt.
Transect Details
| Vessel | Transect # | Date/Time Start | Date/Time End | Start Lon | Start Lat | End Lon | End Lat | Location | Distance (km) | Speed |
|---|---|---|---|---|---|---|---|---|---|---|
| C1 | T01 | 2024-09-15 19:43:03 | 2024-09-15 22:08:52 | -66.491 | 43.567 | -66.490 | 43.237 | GB | 38.94 | 8.65 |
| C1 | T02 | 2024-09-15 22:42:33 | 2024-09-16 01:11:06 | -66.353 | 43.235 | -66.355 | 43.565 | GB | 38.62 | 8.42 |
| C1 | T03 | 2024-09-16 01:43:06 | 2024-09-16 03:30:55 | -66.231 | 43.502 | -66.230 | 43.248 | GB | 29.83 | 8.96 |
| C1 | T04 | 2024-09-16 03:45:06 | 2024-09-16 05:35:52 | -66.174 | 43.248 | -66.175 | 43.505 | GB | 30.30 | 8.86 |
| FM | T01 | 2024-09-15 20:33:29 | 2024-09-15 23:05:03 | -66.470 | 43.569 | -66.470 | 43.234 | GB | 37.99 | 8.12 |
| FM | T02 | 2024-09-15 23:41:28 | 2024-09-16 02:07:12 | -66.333 | 43.235 | -66.332 | 43.567 | GB | 37.55 | 8.35 |
| FM | T03 | 2024-09-16 02:39:46 | 2024-09-16 04:21:35 | -66.221 | 43.504 | -66.220 | 43.249 | GB | 28.78 | 9.16 |
| FM | T04 | 2024-09-16 04:36:30 | 2024-09-16 06:26:39 | -66.163 | 43.247 | -66.164 | 43.505 | GB | 29.25 | 8.60 |
| LB | T01 | 2024-09-15 19:29:22 | 2024-09-15 22:08:37 | -66.401 | 43.567 | -66.401 | 43.235 | GB | 38.07 | 7.74 |
| LB | T02 | 2024-09-15 22:49:17 | 2024-09-16 01:18:27 | -66.265 | 43.233 | -66.263 | 43.566 | GB | 37.97 | 8.25 |
| LB | T03 | 2024-09-16 01:47:21 | 2024-09-16 03:33:37 | -66.192 | 43.502 | -66.192 | 43.247 | GB | 29.02 | 8.85 |
| LB | T04 | 2024-09-16 03:53:31 | 2024-09-16 05:38:16 | -66.135 | 43.249 | -66.136 | 43.504 | GB | 29.07 | 8.99 |
| LJ | T01 | 2024-09-15 19:40:03 | 2024-09-15 22:09:06 | -66.423 | 43.568 | -66.424 | 43.233 | GB | 37.38 | 8.13 |
| LJ | T02 | 2024-09-15 22:45:14 | 2024-09-16 01:11:09 | -66.286 | 43.234 | -66.286 | 43.567 | GB | 37.10 | 8.24 |
| LJ | T03 | 2024-09-16 01:39:53 | 2024-09-16 03:27:10 | -66.202 | 43.504 | -66.201 | 43.250 | GB | 28.32 | 8.55 |
| LJ | T04 | 2024-09-16 03:43:24 | 2024-09-16 05:35:52 | -66.144 | 43.248 | -66.144 | 43.502 | GB | 28.28 | 8.15 |
| LM | T01 | 2024-09-15 19:26:36 | 2024-09-15 21:55:41 | -66.374 | 43.572 | -66.378 | 43.233 | GB | 38.51 | 8.37 |
| LM | T02 | 2024-09-15 22:31:28 | 2024-09-16 00:58:51 | -66.241 | 43.233 | -66.239 | 43.568 | GB | 37.81 | 8.31 |
| LM | T03 | 2024-09-16 01:22:58 | 2024-09-16 03:14:25 | -66.182 | 43.501 | -66.182 | 43.246 | GB | 28.82 | 8.38 |
| LM | T04 | 2024-09-16 03:32:00 | 2024-09-16 05:23:38 | -66.124 | 43.249 | -66.125 | 43.500 | GB | 28.36 | 8.23 |
| MS | T01 | 2024-09-15 19:34:10 | 2024-09-15 22:10:57 | -66.448 | 43.566 | -66.447 | 43.233 | GB | 38.71 | 8.00 |
| MS | T02 | 2024-09-15 22:50:16 | 2024-09-16 01:17:53 | -66.308 | 43.235 | -66.309 | 43.566 | GB | 38.37 | 8.42 |
| MS | T03 | 2024-09-16 01:50:17 | 2024-09-16 03:28:35 | -66.211 | 43.502 | -66.211 | 43.247 | GB | 29.21 | 9.63 |
| MS | T04 | 2024-09-16 03:47:05 | 2024-09-16 05:40:59 | -66.153 | 43.248 | -66.156 | 43.508 | GB | 30.04 | 8.54 |
Survey Summary
| Vessel | Transect No. | Target Strength (db/kg) | Mean Sa (/m2) | Biomass Density (kg/m2) |
|---|---|---|---|---|
| LM | T01 | -35.5 | -43.574 | 0.156 |
| MS | T01 | -35.5 | -49.781 | 0.037 |
| LB | T01 | -35.5 | -49.805 | 0.037 |
| FM | T01 | -35.5 | -49.974 | 0.036 |
| LB | T02 | -35.5 | -51.252 | 0.027 |
| MS | T02 | -35.5 | -52.860 | 0.018 |
| LJ | T01 | -35.5 | -53.498 | 0.016 |
| FM | T02 | -35.5 | -54.592 | 0.012 |
| MS | T04 | -35.5 | -54.949 | 0.011 |
| FM | T04 | -35.5 | -56.064 | 0.009 |
| C1 | T01 | -35.5 | -56.738 | 0.008 |
| LB | T04 | -35.5 | -57.140 | 0.007 |
| LJ | T04 | -35.5 | -57.653 | 0.006 |
| LM | T04 | -35.5 | -57.749 | 0.006 |
| MS | T03 | -35.5 | -57.882 | 0.006 |
| C1 | T02 | -35.5 | -58.323 | 0.005 |
| LJ | T02 | -35.5 | -59.137 | 0.004 |
| C1 | T04 | -35.5 | -60.834 | 0.003 |
| FM | T03 | -35.5 | -61.311 | 0.003 |
| LM | T02 | -35.5 | -61.558 | 0.002 |
| LM | T03 | -35.5 | -61.867 | 0.002 |
| LB | T03 | -35.5 | -62.480 | 0.002 |
| LJ | T03 | -35.5 | -64.194 | 0.001 |
| C1 | T03 | -35.5 | -65.250 | 0.001 |
| Note: | ||||
| Transects are listed from greatest to least backscatter. |
| Layer | Target Strength | Area (km2) | Mean Sa | Density (kg/m2) | Biomass (tons) | Percent Area | Percent Biomass | Standard Error (tons) | Standard Error (%) |
|---|---|---|---|---|---|---|---|---|---|
| German Bank | -35.5 | 826.1781 | -50.722 | 0.0299 | 24,824.032 | 74.2 | 94.8 | 9,953.95 | 40.10 |
| Seal Island | -35.5 | 287.0035 | -58.715 | 0.0048 | 1,368.945 | 25.8 | 5.2 | 268.03 | 19.58 |
Greatest Biomass Densities
A snip from the transect with the greatest biomass density (kg/m2)
The single point with the largest biomass density (kg/m2) was recorded by LM, at the following location:
The transect with the greatest average biomass density (kg/m2) was recorded by LM, at the following location:
Annual Summaries
|
Current Year
|
Previous Year
|
||||||||
|---|---|---|---|---|---|---|---|---|---|
| Ground | Survey Number | Survey Date | HSC Estimate | HSC Turnover Adjusted | Survey Date | HSC Estimate | HSC Turnover Adjusted | DFO Estimate | DFO Turnover Adjusted |
| German Bank | 1 | 2024-08-04 | 12,233 | 12,233 | 2023-08-06 | 2,687 | 2,687 | 2,021 | 2,021 |
| Seal Island | 1 | 2024-08-04 | 45,930 | NA | 2023-08-06 | 1,205 | NA | 929 | NA |
| German Bank | 2 | 2024-08-18 | 14,054 | 11,668 | 2023-08-20 | 4,930 | 4,406 | 3,282 | 2,887 |
| Seal Island | 2 | 2024-08-18 | 6,285 | NA | 2023-08-20 | 1,918 | NA | 897 | NA |
| German Bank | 3 | 2024-09-02 | 15,499 | 12,639 | 2023-09-03 | 9,959 | 8,901 | 8,372 | 7,660 |
| Seal Island | 3 | 2024-09-02 | 3,770 | NA | 2023-09-03 | 2,063 | NA | 1,099 | NA |
| German Bank | 4 | 2024-09-15 | 24,824 | 21,033 | 2023-09-13 | 16,266 | 13,203 | 15,011 | 12,498 |
| Seal Island | 4 | 2024-09-15 | 1,369 | NA | 2023-09-13 | 5,636 | NA | 4,045 | NA |
| German Bank | 5 | NA | NA | NA | 2023-09-27 | 15,242 | 11,360 | 13,503 | 9,978 |
| Seal Island | 5 | NA | NA | NA | 2023-09-27 | 53,844 | NA | 42,269 | NA |
| German Bank | 6 | NA | NA | NA | 2023-10-11 | 23,614 | 20,057 | 26,563 | 23,390 |
| Seal Island | 6 | NA | NA | NA | 2023-10-11 | 15,261 | NA | 14,381 | NA |
| German Bank | 7 | NA | NA | NA | 2023-10-24 | 11,184 | 5,502 | 13,033 | 6,803 |
| Seal Island | 7 | NA | NA | NA | 2023-10-24 | 1,006 | NA | 1,087 | NA |
| Year | Ground | HSC Estimate | HSC Turnover Adjusted | DFO Estimate | DFO Turnover Adjusted |
|---|---|---|---|---|---|
| 2023 | German Bank | 83,882 | 66,116 | 81,785 | 65,237 |
| 2023 | Seal Island | 80,933 | NA | 64,707 | NA |
| 2024 | German Bank | 66,610 | 57,573 | NA | NA |
| 2024 | Seal Island | 57,354 | NA | NA | NA |
Tagging, Plankton, and CTD Data
Summary map
| Vessel | Tags |
|---|---|
Plankton Data
Tow Summary Table
|
Tow 1
|
Tow 2
|
|
|---|---|---|
| Base Details | ||
| Vessel | Lady Melissa | Lady Melissa |
| Set Number | GB2024-05 | GB2024-06 |
| Ground | GB | GB |
| Date | 15/09/2024 | 15/09/2024 |
| Wind Direction (km/h) | W | W |
| Swell (m) | 0 | 0 |
| Air Temp (c) | 18 | 18 |
| Tow Details | ||
| Tow Start | 18:47:00 | 19:06:00 |
| Tow End | 18:57:00 | 19:16:00 |
| Start Lat | 43.56500 | 43.55183 |
| End Lat | 43.55317 | 43.54083 |
| Start Lon | -66.35933 | -66.35083 |
| End Lon | -66.36383 | -66.35100 |
| Avg Tow Depth (m) | 4.806753 | 4.842088 |
| Speed | 5.1 | 4.0 |
| Heading | 198 | 180 |
| Tide Direction | with | against |
| Other Data Collection | ||
| Flow Start | 725125 | 799198 |
| Flow End | 788900 | 862762 |
| No. Revolutions | 63775 | 63564 |
| Distance (m) | 1713.826 | 1708.155 |
| Volume | 5383.983 | 5366.170 |
| Secchi Disappear (m) | 7 | 7 |
| Secchi Reappear (m) | 6 | 6 |
Tow Depth Profiles
Plankton tow depth profile #1
Plankton tow depth profile #2
The first tow is GB2024-05, which was with the tide and had an average depth of 4.8067531m. The second tow is GB2024-06, which was against the tide and had an average depth of 4.8420878m.
Captured plankton
Captured plankton from the surface tows
CTD Data
CTD depth profiles for all 2024 German Bank surveys so far.
Sea surface temperatures
Annual average sea surface temperatures (SST) for German Bank.
Vessel Performance
Speed
Average vessel speed was 8.5. This is above the 8 knot requirement; vessels are urged to slow down to prevent backscatter noise from interfering with the acoustic data.
The speed for each transect are rudimentary and are calculated based on distance. If a significant amount of distance is cut, the speed will appear slower.
Distance
No significant distance was cut from the planned lines; vessels covered the planned area well.